Enable conditional directives by default.

pkg/compiler/lib/src/dart2js.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dart2js.cmdline;
 
 import 'dart:async' show Future;
 import 'dart:convert' show UTF8, LineSplitter;
 import 'dart:io' show exit, File, FileMode, Platform, stdin, stderr;
 
@@ skipping 300 matching lines @@
         '--output-type=dart|--output-type=dart-multi|--output-type=js',
         setOutputType),
     new OptionHandler(Flags.useCpsIr, passThrough),
     new OptionHandler(Flags.noFrequencyBasedMinification, passThrough),
     new OptionHandler(Flags.verbose, setVerbose),
     new OptionHandler(Flags.version, (_) => wantVersion = true),
     new OptionHandler('--library-root=.+', setLibraryRoot),
     new OptionHandler('--out=.+|-o.*', setOutput, multipleArguments: true),
     new OptionHandler(Flags.allowMockCompilation, passThrough),
     new OptionHandler(Flags.fastStartup, passThrough),
-    new OptionHandler(Flags.conditionalDirectives, passThrough),
     new OptionHandler(Flags.genericMethodSyntax, passThrough),
     new OptionHandler('${Flags.minify}|-m', implyCompilation),
     new OptionHandler(Flags.preserveUris, passThrough),
     new OptionHandler('--force-strip=.*', setStrip),
     new OptionHandler(Flags.disableDiagnosticColors,
         (_) => diagnosticHandler.enableColors = false),
     new OptionHandler(Flags.enableDiagnosticColors,
         (_) => diagnosticHandler.enableColors = true),
     new OptionHandler('--enable[_-]checked[_-]mode|--checked',
         (_) => setCheckedMode(Flags.enableCheckedMode)),
@@ skipping 17 matching lines @@
     new OptionHandler(Flags.disableTypeInference, implyCompilation),
     new OptionHandler(Flags.terse, passThrough),
     new OptionHandler('--deferred-map=.+', implyCompilation),
     new OptionHandler(Flags.dumpInfo, setDumpInfo),
     new OptionHandler(
         '--disallow-unsafe-eval', (_) => hasDisallowUnsafeEval = true),
     new OptionHandler(Option.showPackageWarnings, passThrough),
     new OptionHandler(Flags.useContentSecurityPolicy, passThrough),
     new OptionHandler(Flags.enableExperimentalMirrors, passThrough),
     new OptionHandler(Flags.enableAssertMessage, passThrough),
+    // TODO(floitsch): remove conditional directives flag.
+    // We don't provide the info-message yet, since we haven't publicly
+    // launched the feature yet.
+    new OptionHandler(Flags.conditionalDirectives, (_) {}),
     new OptionHandler('--enable-async', (_) {
       diagnosticHandler.info(
           "Option '--enable-async' is no longer needed. "
           "Async-await is supported by default.",
           api.Diagnostic.HINT);
     }),
     new OptionHandler('--enable-null-aware-operators', (_) {
       diagnosticHandler.info(
           "Option '--enable-null-aware-operators' is no longer needed. "
           "Null aware operators are supported by default.",
@@ skipping 405 matching lines @@
       } else if (exitCode == 253) {
         print(">>> TEST CRASH");
       } else {
         print(">>> TEST FAIL");
       }
       stderr.writeln(">>> EOF STDERR");
       subscription.resume();
     });
   });
 }